Beamer – How to Uncover Underbrace in Math Mode

beamermath-mode

I've got an underbrace (\underbrace{foo}_{bar}) which I want to uncover (i.e. foo should be there from the beginning, while the underbrace and the bar should be uncovered on the next slide. I've tried the following, which (not surprisingly) doesn't work:

\documentclass{beamer}

\begin{document}
\begin{frame}
  Without uncover (this is what it should look like on the second subframe):
  \begin{displaymath}
    \underbrace{foo}_{bar}
  \end{displaymath}
  With uncover (doesn't work):
  \begin{displaymath}
    \uncover<2>{\underbrace}{foo}\uncover<2>{_{bar}}
  \end{displaymath}
\end{frame}
\end{document}

In the second displaymath, the underbrace is displayed before foo and the bar as index to foo, and moreover the underbrace is immediately visible.

Note that \only wouldn't be a solution because on one hand in my actual document I use \setbeamercovered{transparent} so the underbrace and the text below should be lightly visible from the beginning, and on the other hand \only would also not keep the space for the underbrace.

So how can I achieve that?

Best Answer

One way to do that, is to use the definition of the transparency (15% Text foreground on the background and to avoid the “jumping” use as suggested here the overprint environment.

Though you have to define your term that's \underbraced twice and in my quick hack the transparency color is the one mentioned above, because i didn't find whether i can somehow get that by \usebeamercolor

\documentclass[transparent]{beamer}
\usepackage{amsmath}
\usepackage{cancel}
\begin{document}
    \setbeamercovered{transparent}
    \begin{frame}%
        \begin{overprint}
            \onslide<1>\begin{displaymath}
                \color{normal text.fg!15!normal text.bg}
                \underbrace{\usebeamercolor[fg]{text}foo}_{bar}
            \end{displaymath}
            \onslide<2>\begin{displaymath}
                \underbrace{foo}_{bar}
            \end{displaymath}
        \end{overprint}
    \end{frame}%
\end{document}

And (thanks to @Andrew Stacey) the even shorter version just switching colors using \only (because \color is sensitive to that) would be

\begin{frame}
    \begin{displaymath}
        \color{normal text.fg!15!normal text.bg}
        \only<2->{\color{normal text.fg}}
        \underbrace{\usebeamercolor[fg]{text}foo}_{bar}
    \end{displaymath}
\end{frame}

Related Solutions

Beamer Enumerate – Continuing Counters in LaTeX

Use \resetcounteronoverlays to ensure that your counter is automatically reset on subsequent slides of a frame:

\resetcounteronoverlays{saveenumi}

A complete example using your code:

\documentclass{beamer}
\setbeamercovered{highly dynamic}

\newcounter{saveenumi}
\newcommand{\seti}{\setcounter{saveenumi}{\value{enumi}}}
\newcommand{\conti}{\setcounter{enumi}{\value{saveenumi}}}

\resetcounteronoverlays{saveenumi}

\begin{document}

\begin{frame}[<+->]
  \begin{enumerate}
  \item foo
  \item bar%
    \seti
  \end{enumerate}
\end{frame}

\begin{frame}[<+->]
  \begin{enumerate}
    \conti
  \item zip
  \item yadda%
    \seti
  \end{enumerate}
\end{frame}

\end{document}

enter image description here

Beamer – How to Create a Permanent Transparent Block in a Frame

Quoting the manual:

\invisible<⟨overlay specification⟩>{⟨text⟩}

This command is the opposite of \visible.

So, what does \visible do? Quoting again the manual:

\visible<⟨overlay specification⟩>{⟨text⟩}

This command does almost the same as \uncover. The only difference is that if the text is not shown, it is never shown in a transparent way, but rather it is not shown at all. Thus, for this command the transparency settings have no effect.

Therefore, if you really want to have the second block transparent, you don't have to use \invisible.

You can use \onslide for example, of course by specifying first \setbeamercovered{transparent}:

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{mwe}% for dummy images
\usepackage{amsmath}
\usetheme{CambridgeUS}
\setbeamercovered{transparent}
\begin{document}
\begin{frame}
\only<1>{
\begin{block}{procedure-1}
 \centering% use this and not the center environment
 \includegraphics<1>[height=1.3in,width=4in]{example-image}
\end{block}
}
\only<2>{
\begin{block}{procedure-2}
 \centering% use this and not the center environment
 \includegraphics<2>[height=1.3in,width=4in]{example-image-a}
\end{block}
}
\only<3->{
\begin{block}{procedure-3}
 \centering% use this and not the center environment
 \includegraphics<3->[height=1.3in,width=4in]{example-image-c}
\end{block}
}
\onslide<4>{
\begin{block}{Mathematical Formulation}
\begin{equation}
 0+0=0
\end{equation}
\end{block}
}
\end{frame}
\end{document}

The result:

enter image description here

Best Answer

Related Solutions

Beamer Enumerate – Continuing Counters in LaTeX

Beamer – How to Create a Permanent Transparent Block in a Frame

Related Question